1. Field of the Invention
The present invention relates to an arithmetic processor for measuring bone density using a correspondence relationship between a luminance value of transmitted radiation and a thickness of a reference material, the luminance value being obtained by applying radiation, which is emitted from a radiation source upon application of a tube voltage to the radiation source, to the reference material having different thicknesses and detecting the radiation transmitted through the reference material, and a bone density measuring device provided with the arithmetic processor.
2. Description of the Related Art
Conventionally, the MD method, the DIP method, etc., for example, are known as methods for measuring bone mineral content to check growth status, or the like, of human bones. In the MD method taught in Japanese Unexamined Patent Publication No. 2006-334046 (hereinafter, Patent Document 1), an aluminum step wedge is imaged under the same imaging conditions as those used for X-ray imaging of a body site to be measured of the subject, and the result of the imaging is used to perform correction for variation among photoelectric conversion elements forming the sensor and correction for aging of the sensor element. The imaging conditions can be inputted via an imaging condition input unit, and the inputted imaging conditions are displayed on an imaging condition display area.
In the DIP method taught in Japanese Patent No. 2793502 (hereinafter, Patent Document 2), an aluminum scale and the palms of the subject are placed on an X-ray film and are imaged using an X-ray with a tube voltage of 50 kV being inputted and set. In imaging conditions in the DIP method, usually, a tube voltage of 50 kV, which provides the best correlation between the bone (hydroxyapatite) and the aluminum, is set as a recommended tube voltage.